Currently there are weighing machines comprising two parallel chain drives between which carriages are arranged, joined to the chains so that the coordinated motion of these in the same direction makes the carriages move along a closed path in which conventionally a horizontal straight upper advance section, a lower horizontal straight return section and certain curved sections are distinguished. Buckets are attached to these carriages, and the machines comprise a plurality of work stations distributed along the path of the carriages, and by extension along the path of the buckets attached to the carriages, such as a loading station where fruit is fed into the buckets; a weighing station where the fruit contained in each bucket is weighed; and an emptying or unloading station where the buckets are emptied.
In so-called combination weighing machines, several buckets are attached to the same carriage, and at the emptying station there is a selective emptying of the buckets whose total fruit weight is closest to a predetermined value.
An example of a weighing machine of the type described above is found in patent document EP 0982570.
The form of the buckets varies as a function of the needs and the nature of the products that must be transported, but it is necessary that the type of weighing machines previously described, which use similar transport systems, control the inclination of the buckets so that they do not accidentally spill the products contained inside them during transportation.
Conventionally, in order to guarantee that the buckets maintain the same orientation during their path, at their ends, the carriages are connected in an articulated way to the chains, or mounted to rotate around the axes of the chains, and the transport system is completed with rails or guides in which runners, bearings or similar devices that have the same effect on the carriages, are inserted in slide mode. This form of control is necessary to maintain the orientation of the carriages and, therefore, of the containers secured to the carriages during the curved sections that link the straight upper advance section and the lower straight return section. An example of orientation control based on rails or guides on a weighing machine of the type previously described is exemplified in the patent document EP 0803716.
The use of these rails or guides, however, has serious problems of wear and noise from the machines, which require a lot of work in maintenance and reparation.
An objective of the present invention is a transport system of buckets specifically designed to transport buckets in a combination weighing machine that solves these problems, meaning that it allows the rails or guides used by the known systems to be suppressed in order to control the orientation of the carriages on the curved sections of the closed path.
Through the patent document JP 2000118667, knowledge is available on a transport system for trays that could be suitable for transporting buckets in a weighing machine. The system proposed in JP2000118667 sets forth the characteristics according to the preamble of claim 1 of the present patent application.
Although the system described notably improves the control of the orientation of the trays, especially on straight sections through the use of two chains that are horizontally offset and by joining of the carriages to each chain through individual arms which are also horizontally offset at the same distance as the difference between chains, it still needs to use a rail or guide into which a follower element mounted on each carriage is inserted in slide mode during the curved sections of the path of these carriages in order to maintain the desired orientation. The difference between the chains makes it so that there is much less mechanical interference between the rail and the followers, and therefore makes it possible to reduce the wear of these components, but it does not avoid the fact that rails or guides will still need to be used in order to guarantee a proper orientation in this case of the trays.